Until recently, the ability to polyadenylate RNA has been widely viewed as a special property of eukaryotic cells, where polyadenylation has an important role in generating functional messenger RNA and regulating its decay. Recent work has shown that polyadenylation of RNA has important biological effects in prokaryotes as well. The long term goal of this multifaceted project is to understand the genetics and biochemistry of polyadenylation in prokaryotes and to elucidate its biological function(s). Its specific aims are to: 1) define the structural features of RNAs that determine their susceptibility to polyadenylation, 2) identify and characterize the genes and enzymes that mediate the specificity of adenylation and its effects on RNA decay, and 3) elucidate the effects of polyadenylation on gene expression, and particularly on the translation of messenger RNA. These investigations will use genetic and biochemical approaches, including oligonucleotide-directed mutagenesis to identify signals that trigger polyadenylation, in vivo enzymatic assays and novel genetic approaches to identify and functionally characterize bacterial enzymes and genes that govern polyadenylation and its effects, and mutational and biochemical analyses of the biological consequences of polyadenylation. The work will provide important basic knowledge about factors that affect microbial evolution and gene expression, and consequently the growth and development of microbes that produce human disease. Such an understanding is likely to also yield information of practical value for the manipulation of biological processes affected by RNA, including the production of medically important gene products in bacterial cells.